A mat is placed in a slip-free manner on carpet that is laid underneath. In one aspect, a user is requested to select a ratable object. The forming of the interposer includes, forming a dielectric layer on the dummy substrate, forming a pattern and a via on the dielectric layer, and forming a seed layer at the pattern and the via of the dielectric layer and forming a redistribution layer and a conductive via on the seed layer. By providing a cradle, having respective cradle sides projecting from a junction in association with a drive mechanism and each side of the cradle coupled to a pivot arm, control of rotation paths can be achieved. An adder circuit receives and sums the dithered input signal word and the carrier signal word to produce the digital tuning word.